Multi-chamber syringe

ABSTRACT

A syringe has a floating barrier seal located at approximately the middle of the syringe chamber, thereby forming (at least) two different chambers on opposite sides of the barrier to provide separate storage space for (at least) two different medicines. A hypodermic needle projects inwardly into the adjacent one of the chambers, far enough to pierce the floating barrier after the first medicine has been substantially all dispensed. The needle passes through the barrier to dispense the second medicine on the other side of the barrier, at which time there is a relief of back pressure which otherwise would result from a compression of the first medicine. At this time, the barrier seals the first medicine away from the needle so that it cannot mix with or contaminate the second medicine. A catch may be provided to prevent the barrier from raising and thereby allows the first medicine to reach the needle after the second medication has begun to flow.

United States Patent 11 1 Weingarten July 29, 1975 1 1 MULTI-Cl-IAMBERSYRINGE [75] Inventor: Charles Z. Weingarten, Evanston,

Ill.

22 Filed: Nov. 2, 1973 211 Appl. No.: 412,164

Related US. Application Data [63] Continuation-impart of Scr. No.255,099, May 19,

1972, abandoned.

[52] US. Cl. 128/218 R; 128/218 N [51] Int. Cl. A61 [58] Field of Search128/221, 218 N, 218 R,

128/218 D, 218 DA, 220, 215, 216, DIG 5, 128/276, 218 M, 218 NV, DIG.28: 215/6; 206/219-222 1,201,009 9/1965 Germany 128/218 R 488,00312/1953 Italy 128/221 934,524 8/1963 United Kingdom 128/218 R PrimaryExaminer-Richard A. Gaudet Assistant Examiner-J. C. McGowan Attorney,Agent, or Firm-Powell L. Sprunger [57] ABSTRACT A syringe has a floatingbarrier seal located at approximately the middle of the syringe chamber,thereby forming (at least) two different chambers on opposite sides ofthe barrier to provide separate storage space for (at least) twodifferent medicines. A hypodermic needle projects inwardly into theadjacent one of the chambers, far enough to pierce the floating barrierafter the first medicine has been substantially all dispensed. Theneedle passes through the barrier to dispense the second medicine on theother side of the barrier, at which time there is a relief of backpressure which otherwise would result from a compression of the firstmedicine. At this time, the barrier seals the first medicine away fromthe needle so that it cannot mix with or contaminate the secondmedicine. A catch may be provided to prevent the barrier from raisingand thereby allows the first medicine to reach the needle after thesecond medication has begun to flow.

17 Claims, 13 Drawing Figures [56] References Cited UNITED STATESPATENTS 2,607,344 8/1952 Brown 128/218 D 2,687,728 8/1954 Copen 128/218D 2,753,990 7/1956 Chaflin ct al. 215/6 X 2,939,459 6/1960 Lazarte eta]. 128/218 M 3,200,813 8/1965 Christakis 128/272 X FOREIGN PATENTS ORAPPLICATIONS 996,168 6/1965 United Kingdom 128/218 M e: z i i 5 5 x s Ii I s IIAi/I I 11/ III IIIIIIIIII7III1 PATENTED J L29I975 SHEET F G-F|G.3

FIGJ

PATENTEI] JUL29 I975 IIIIIIIIII SHEET 2 III/711111 7A MULTl-CHAMBERSYRINGE This is a continuation-in-part of my earlier filed, copendingapplication Ser. No. 255,099,-, filed May 19, 1972, now abandoned.

This invention relates to syringes ,for giving multimedicine injectionsand, more particularly, to syringes which do not allow two or moremedicines to mix prior to their sequential injection-into a patient.

Syringes are used to inject medicine into the body of a human or ananimal. Usually, the injected medication is a single fluid or a mixture,in which case the syringe has a single compartment and asingle needle.Sometimes, the medication includes two chemicals or drugs which must bemixed immediately prior to the injection. Here, the syringe usually hastwo compartments separated by a barrier which either ruptures or opensat the time of injection so that the injected medicine is a singlechemical mixture as it passes into the patients body. I

When it has been necessary to inject two separate and unmixed chemicals,the customary practice has beento use two separate syringes. Thisdoubles the cost of preparing and administering themixtures forinjection, and it doubles the pain by requiring two punctures of thepatients skin.

A suggested alternative is to provide twin, rigidly interconnectedsyringes which does nothing for the cost, but supposedly gives a singlesensation of pain since the two needles are physically too closetogethe'r'to be perceived as more than a single point of'contact. Asidefrom the" double cost, this twin syringe requires greater skill on thepart of the doctor or nurse administering the medication. a

The foregoing assumes the syringe is being used for injection. However,syringes are also used for extraction by creating a vacuum in thechamber. In essence, by reversing the process of injection one is ableto produce an extraction. l

' Accordingly, an object of this invention is'ftoprovide a syringeforadministering two medications which are completely separate and unmixedat the timeof injection. Here an object is to provide a syringe hailingsubstantially the same cost as a single medica'tion syringe. In' thisconnection, an object is to provide a disp osable, double compartmentsyringe having s'ucha l'ow'cost that it may be filled with two or more rne'dications and prepackaged in a sterile container by a pharmaceuticalcompany. I a

Another object is to enable the unimpeded flow of a second medicationbyprecluding the back pressure which otherwise r'night build from theremaining portions of the first medication This object is acco mplishedby having a point "of evacuatio'n in the first chamber which iseffective afterthe s econd medication has begun to flow,thus enablingthat 'ch'ambers ual medication to be released] i M I The object,furthermore, is to convert amultip le chamber syringe which may be usedfor an injection, into a single chamber syringe, whichmay be used forextraction. This object is accomplished by capturing the floatingbarrier dividing .the twocompartments at; the base of the syringe,chamber. In this way the object of converting to a single Chambersyringe achieved,

Moreover, an object of the invention is toreduce the;

skill level required to administera m' ulti-rne'dic ation in-. jection.Here, an object is to reduce the patientspain 7 this choice allows theuse :oflthe most economical .and psychological suffering in anticipationof and during the injection.

lnkeeping-with an aspect of this invention, these and other .objects of,the invention are accomplished by a syringe having a floating barriertherein at approximately the middle of the syringe chamber. Twodifferent chambers are thereby. formed on opposite sides of .thefloatingbarrier to separate the two different medi- .c-ations. Asinglehypodermic needle projects inwardly into the bottom of a first of thechambers far enough to pierce thefloating barrier after substantiallyall of the first medication has been dispensed. The needle passesthrough the barrier to thereafter dispense the second medication on theother side of the barrier. In this .way, the barrier seals the firstmedication away from the needle so that it cannot mix with orcontaminate the second medication. At this time, the residual medicationis released through a point of evacuation of the first chamber, thusprecluding back pressure from the second medication. Moreover, ifdesired, the floating barrier may be captured at the base of thechamber, thus enabling the syringe tobe used for extraction.

The nature of a preferred embodiment of the invention may beunderstoodbest from an inspection of the attached drawings wherein: r

I FIG. 1 is anexplodedview, in perspective, of the inventive syringe;

FIGS. 2-5 are stop motion views schematically showing how twomedications are separately dispensed so that neither mixes with orcontaminates the other prior qi ie 3 FIG. 6.schematically shows ,thefirst embodiment. of evacuating the remainderof a first medication after.it is no longer being injected into a patient; FIG. 7 perspectivelyshows a second embodiment of the needleassembly for evacuation ofmedication;

FIG, 8shows perspectively a third embodiment with absorbent material toaccumulateescaping medication and prevent a dribbling of the. firstmedication atthe port;

FIG, 9 is a cross sectipn view ofafourth embodiment utilizing thesyringe tube as a point for a weakened rupture area; v L

FlG. 10 perspectively shows a fifth embodiment with a,weakened area inthe needle assern blytari dj i 11 -13 are partlycross sectional andpartly perspective, views of several embodiments for capturing thefloating barrier in order to enable the syringe to be used forevacuation. This is. a very sophisticated syringe into which manyoptional features can be easily incorporated. O nesuch option providesan evacuation port which will preclude any buildup of back pressure.This port can be a weakenedwall structureor a stationary outlet with anyof various forms of peel off tabs. Due to the equal effectiveness ofany; such means, the manufacturer may select the onemeans which issuited to his manufacturing or processing. procedure. Another easilyincorporated,

opt ion enables this syringe to be used for extractionas well asinjection by either simply modifying the design ofthe needle ortheinside-wall'o f the chamber. Again means forthe manufacture rsfacilities. V

.The.inventivesyringe comprises a needle assembly 2l.,ta cylinder 22, afloating barrier seal 23, and a plunger assembly 24. The needle isseparated into first and second parts 26,27, respectively. The firstpart 26 is sharpened and adapted to pierce the skin of a person oranimal receiving the medication. The second part 27 of the needleprojects into the cylinder 22 for a distance which is adequate topuncture the barrier 23 when it teaches the bottom of the cylinder. Apreferably plastic collar 28 is firmly attached to the needle 21 at thejunction point between the two parts 26, 27. The collar 28 includes twooppositely disposed ears 29, 30 which cooperate with internal threads inthe syringe to attach the needle thereto.

The cylinder 22 is an elongated hollow tube of uniform cross section,terminated at the bottom in an internally threaded coupler 35.Concentrically positioned inside coupler is a tube 36 having an axialopening therein to receive the needle 27 with a sufficiently tight sealto preclude leaking. The threads 37 inside the coupler 35 engage andreceive the ears 29,30 on the collar 28. Thus, as the assembly 28 isrotated, the two parts 28,35 come together with a tight seal.

The upper end of the cylinder 22 has opposing tabs 38, 39 which are heldby the index and middle fingers of the person administering theinjection. The upper end 40 of the cylinder 22 is beveled to provide aconical entrance for guiding and directing the barrier 23 and plunger 24members upon entrance into the cylinder. The entire unit is preferablymade from low cost, this-walled, transparent plastic material so thatthe person administering the injection can watch the operation to besure that the medications are properly fed into the patient.

According to one aspect of this invention, a floating barrier member 23is provided for forming two separate chambers in the tube. Preferably,this barrier is a soft rubber plug which has two longitudinallydisplaced piston rings 41,42 for making a good seal against the interiorwall of the cylinder 22. The bottom 44 of the plug is somewhat conicalto help guide it on its entrance into the cylinder 22. An axial bore 45almost completely pierces the plug forming the floating barrier member23. However, the bottom of the bore 45 does not quite extend through thebottom of the plug. Therefore, the bottom of the bore 45 is covered by athin membrane 46 to prevent any fluid from passing through the barrier.

The plunger assembly 24 comprises a ram rod 50 having a soft rubber plug51 attached to the bottom and a thumb pad 52 attached to the other end.The plugs 23 and 51 are almost identical, both slide inside the cylinder22.

The method of its use is illustrated by the stop motion views of FIGS.2-5. Preferably, a pharmaceutical manufacturer loads the inventivesyringe in his laboratory or factory by depositing a first medicine 54in the bottom of the cylinder 22. Then, the barrier 23 is placed in thetube and brought down into contact with the top of the medicine surface,to eliminate all entrapped air. One way of doing this is to invert thesyringe, allow the entrapped air to escape through a tube locatedintermediate the barrier 23 and cylinder 22, and then to seal the tube.

After the first medicine 54 is loaded into the first compartment, asecond medicine 55 is loaded into the second compartment. Then theplunger assembly 24 is brought down into contact with the upper surfaceof the second medicine, and all entrapped air is withdrawn. One way towithdraw the entrapped air is to slip a small tube of hypodermic needlestock between the soft rubber plug 51 and the inside surface of thecylinder 22 and to vacuum pump the air from the upper chamber. Theinventive syringe (FIG. 2) is now preloaded with two completelyseparated medications 5455, held securely apart, one from the other.

As the injection is given (FIG. 3), only the first medicine passes outof the chamber 22 and through the necdlc 26, into the patient. As thefirst medicine is exhausted, the floating barrier 23 engages and ispierced by the upper end 27 of the needle 21. It is easy to so piercethe floating barrier since only the thin membrane 46 is present at thispoint. Thereafter, the needle end 27 is in the bore 45 which provides anunimpeded passage for the medicine in the upper chamber. The rubber-likematerial of the floating barrier surrounds and seals the outside of theneedle 27 and prevents any more of the first medicine 54 from passingthrough the needle.

At this time (FIG. 4), the second medicine 55 passes through the needle27 and into the patient receiving the injection. The second medicine isnot mixed with or contaminated by the first medicine at any time beforeor during the injection.

At the bottom of the stroke (FIG. 5), the plug 51 reaches the top of thebarrier 23 or the needle 27, where it terminates the flow of themedicine through the needle. The medicine is now exhausted, and thespent syringe is discarded.

It is apparent that the same principle may be extended to anadministration of a larger number of medicines by increasing the numberof floating barriers and, therefore, the number of separate compartmentsinside the cylinder 22. The membrane member 46 is thin enough and therubber plug 23 is soft enough to admit the second medicine 55 to theneedle. However, sometimes the first medicine 54 entrapped under thefloatingbarrier 23 should be evacuated to relieve pressure and to allowthe barrier 23 to settle further into the cylinder 22. This isespecially true if there are two or more floating barriers. The firstbarrier must settle to allow the second barrier to be pierced by theneedle 27.

Therefore, another aspect of this invention is to insure the flow ofmedication after the barrier reaches the needle top by relieving anypossible back pressure in the first chamber. This is accomplished byincorporating a port for evacuation of the first chamber, into thedesign inventive syringe 20. There are several possibilities for boththe placement of this port and a method of evacuation (FIGS. 6-10).

The first embodiment involves a weakening of c'ylinder 22 at a point 60in the entrapped area 61. An adjacent chamber 62 is positioned tocommunicate with the entrapped area 61 when the weakened point 60ruptures. As the first medicine 54 is ejected from the cylinder 22, thepressure does not exceed the rupture strength of the weakened area 60.However, when the medication 54 flow is blocked by the needle end 27passing through the floating barrier, the fluid pressure builds in theentrapped area 61. weakened area 60 ruptures under the augmentedpressure, and the entrapped medication flows from area 61 into a closedand, perhaps, evacuated chamber 62. As the fluid flows from area 61, thebarrier 23 settles further into cylinder 22 in order to enable theneedle end 27 to properly perform its penetration function. There cannotbe a reverse flow since the punctured membrane 46 of the floatingbarrier 2 3 seals itself around the outside periphery of the needle.Moreover, any pressure differential is such that the flow will be fromthe cylinder 22 into the chamber 62.

A second embodiment of a syringe device with an evacuation port (FIG. 7)has the location of the evacuation port 74 in collar 28 of the needleassembly 21. This evacuation port 74 has a flexible plastic peel off orotherwise removable tab 70. Preferably, an adhesive is applied to aportion of the removable tab 70 to form adhesive cover portion 71 whichis large enough to cover the port 74. This tab is affixed to collar 28,over evacuation port 74, thus sealing it from premature evacuation ofthe first medication 54 during the injection thereof. The nonadhesiveedge of the removable tab 70 forms tab grip 72. By holding tab grip 72between index finger and thumb or by catching it with a fingernail, onecan easily peel the adhesive cover 71 from collar 28. This procedure isused to release entrapped medication 54. After peeling the removable tab70 from the collar 28, any entrapped medication 54 flows through theevacuation port 74, thus relieving back pressure.

Yet another embodiment for evacuation (FIG. 8) is a variation of thesecond embodiment (FIG. 7). This variation provides a means foraccumulating or sponging up the first medication 54 after its releasethrough evacuation point 74. Here the peel off tab 76 is somewhat in thenature of an adhesive bandage. A nonreleasable adhesive binds thestraight or vertical fastener portion 80, to the plastic collar 28.Bulge 78 holds a pad of absorbent material 82 in a position to catch themedication at port 74 when the syringe is in a generally verticalposition. Therefore, when first medication 54 is released, by pushingback the tab portion 71, it is soaked up by absorbent material 82.

Still another embodiment for total evacuation (FIG. 9 and 10) isessentially the first embodiment (FIG. 6) without provision of anevacuation chamber 62. Here, weakened area 86 in the syringe ruptureswhen pressure builds from first medication 54 becoming entrapped underfloating barrier 23. However, instead of utilizing an adjacent chamber,the entrapped medication simply flows from cylinder 22, thus enablingfloating barrier 23 to settle. In FIG. 10, the location of the weakenedwall structure 88 is in the collar 28 of the needle assembly. The choiceof location, with comparable effectiveness, enables a manufacturer tochoose the position best suited to its manufacturing techniques.

A further aspect of this invention is to provide a syringe which is notonly capable of injecting, but also of extracting. Therefore, themultiple chamber inventive syringe is made capable of converting itselfinto a single chamber syringe. This is accomplished by capturing thefloating barrier 23 at the base of cylinder 22 thus enabling inventivesyringe 20 to perform as if it were a single chambered device.

As shown in FIG. 12, a capture means is provided in the form of two ormore bosses or knobs 92 and 94 which are molded on the inside surfacewalls of the cylinder 22. Their distance from the base of cylinder 22 isslightly greater than the height of floating barrier 23. These bosses orknobs 92 and 94 are small enough to enable the flexible material atpiston rings-41 and 42 to slide over them during injection; yet largeenough to trap floating barrier 23 at the base of cylinder 22 duringextraction. The lower and upper edges of the bosses 92,

94 may be shaped to enable the barrier to be captured and yet topreclude any release thereof. The trapping of floating barrier 23converts cylinder 22 into a single chamber and therefore enables theinventive syringe 20 to be used for extraction. after evacuation ofsecond medicine 55.

In FIG. 11, the capture means is a cone preferably made by an expansionofa hypodermic needle. It could also be a separate piece slipped on overthe needle and dimpled in place. Cone 90 is positioned at the top ofsecond part 27 at needle to trap floating barrier 23 at base of cylinder22. The diameter of the base of cone 90 is formed relative to thediameter of the axial bore 45 for enabling it to trap floating barrier23 after clearing the top of it. The soft rubber construction offloating barrier 23 affords little resistance as cone 90 passes throughaxial bore 45.

In the FIG.. 13'modification, the design of the needles second part 27includes a barb-like capture means. Here, the tip of the second part 27is bent back upon itself to formi-a hook 96. The top end of the hook maybe sharpened to facilitate a penetration of the barrier. Hook 96 holdsfloating barrier 23 stationary after clearing the top of it. Since thematerials of both the needles second part 27 and floating barrier 23 arequite flexible, little resistance is encountered as hook 96 passesthrough axial bore 45.

The wall of the bent needle may be broken at the top or it may be leftintact so that medication centers the needle at the barb end of thehook, which is pointing downward in FIG. 13. Due to the pressure ofmedication flowing around the needle, the medication may enter the barbend of this point as effectively as the end of a straight hypodermicneedle. This enables manufacturers to simply use a bent section ofconventional hypodermic needle stock, rather than to produce a specialclosed end. I

It should be understood that modifications may be made without departingfrom the scope of the invention. Therefore, the appended claims shouldbe construed to cover all equivalent structures.

I claim:

1. A multi-chamber syringe, comprising: a cylinder having a cavity, aplunger having one end received in the cavity, at least one floatingbarrier means in said cavity forming at least first and second fluidchambers first and second liquids in said first and second chambers,needle means communicating with the first chamber and projecting intosaid cavity a sufficient distance to puncture said barrier means andcommunicate with the second chamber when said barrier means nears theend of its travel as said syringe is emptied, openable port means forselectively relieving back pressure on said barrier means without mixingsaid liquids in said first and second chamber, whereby said barriermeans may continue to settle after having relieved said pressure andmeans for selectively opening said port means.

2. The syringe of claim 1 wherein said floating barrier means comprisesa soft plug having at least one integrally formed circumferential pistonring and an axial bore closed by a membrane.

3. The syringe of claim 1 wherein said port means comprises anevacuation port in a wall of said cylinder. 4. The syringe of claim 3wherein said evacuation port comprises an opening having a tabassociated therewith for opening said port, and absorbent means adjacentthe opening for accumulating at least some of the liquid passing throughsaid opening.

5. The syringe of claim 3 wherein said evacuation port comprises anopening having a peel off closing tab associated therewith for openingsaid port.

6. The syringe of claim 3 including means associated with said port foraccumulating at least some of the liquid after relief of said backpressure.

7. The syringe of claim 1 including means for capturing said barriermeans after said puncture whereby the second chamber may be used forextraction.

8. The syringe of claim 7 wherein said capture means comprises meansassociated with the internal wall of said cylinder.

9. The syringe of claim 7 wherein said capture means comprises meansassociated with the end of said needle means which punctures saidbarrier means.

10. The syringe of claim 7 wherein said capture means comprises anenlarged portion of the needle means adjacent its puncture end.

11. A syringe comprising a cylinder having a floating barrier therein, apiston having one end received in the cylinder, a needle extending intosaid cylinder to pierce said barrier with an end of the needle at apredetermined point in the stroke of said piston, means for capturingsaid barrier when punctured, whereby said syringe may be used forinjection before capture of the barrier or for extraction after capturemeans for relieving pressure in the syringe at least prior to completepassage of the needle through the barrier.

12. A syringe assembly, comprising:

a cylinder having a fluid receiving cavity:

a plunger having one end received in one end of the cavity;

a floating barrier means received in the cavity and defining first andsecond chambers, said second chamber being located intermediate thebarrier means and the plunger;

needle means adjacent the other end of the cavity,

said needle means projecting into and communicating with said firstchamber, said needle means puncturing the barrier means andcommunicating with the second chamber when the barrier means is movedtoward the needle means responsive to movement of the plunger into thecavity;

means for capturing the barrier means adjacent the other end of thecavity with the needle means communicating with the second chamber,whereby the plunger may be withdrawn for subsequent use of the secondchamber in pumping fluid means for relieving pressure in the firstchamber at least prior to complete passage of the needle through thebarrier means.

13. The syringe assembly of claim 12 wherein the capturing meanscomprises, an enlarged portion of the needle means for retaining thebarrier means after the needle means punctures the barrier means.

14. The syringe assembly of claim 13 wherein the enlarged portion of theneedle means comprises a cone adjacent the puncturing end of the needlemeans.

15. The syringe assembly of claim 13 wherein the enlarged portion of theneedle means comprises a barb adjacent the puncturing end of the needlemeans.

16. The syringe assembly of claim 12 wherein the capturing meanscomprises, an enlarged portion on the inner surface of the cylinder andlocated adjacent the barrier means in the second chamber after thebarrier means is punctured by the needle means.

17. The syringe assembly of claim 16 wherein the enlarged portioncomprises a plurality of bosses on the inner surface of the cylinder.

1. A multi-chamber syringe, comprising: a cylinder having a cavity, aplunger having one end received in the cavity, at least one floatingbarrier means in said cavity forming at least first and second fluidchambers first and second liquids in said first and second chambers,needle means communicating with the first chamber and projecting intosaid cavity a sufficient distance to puncture said barrier means andcommunicate with the second chamber when said barrier means nears theend of its travel as said syringe is emptied, openable port means forselectively relieving back pressure on said barrier means without mixingsaid liquids in said first and second chamber, whereby said barriermeans may continue to settle after having relieved said pressure andmeans for selectively opening said port means.
 2. The syringe of claim 1wherein said floating barrier means comprises a soft plug having atleast one integrally formed circumferential piston ring and an axialbore closed by a membrane.
 3. The syringe of claim 1 wherein said portmeans comprises an evacuation port in a wall of said cylinder.
 4. Thesyringe of claim 3 wherein said evacuation port comprises an openinghaving a tab associated therewith for opening said port, and absorbentmeans adjacent the opening for accumulating at least some of the liquidpassing through said opening.
 5. The syringe of claim 3 wherein saidevacuation port comprises an opening having a peel off closing tabassociated therewith for opening said port.
 6. The syringe of claim 3including means associated with said port for accumulating at least someof the liquid after relief of said back pressure.
 7. The syringe ofclaim 1 including means for capturing said barrier means after saidpuncture whereby the second chamber may be used for extraction.
 8. Thesyringe of claim 7 wherein said capture means comprises means associatedwith the internal wall of said cylinder.
 9. The syringe of claim 7wherein said capture means comprises means associated with the end ofsaid needle means which punctures said barrier means.
 10. The syringe ofclaim 7 wherein said capture means comprises an enlarged portion of theneedle means adjacent its puncture end.
 11. A syringe comprising acylinder having a floating barrier therein, a piston having one endreceived in the cylinder, a needle extending into said cylinder topierce said barrier with an end of the needle at a predetermined pointin the stroke of said piston, means for capturing said barrier whenpunctured, whereby said syringe may be used for injection before captureof the barrier or for extraction after capture means for relievingpressure in the syringe at least prior to complete passage of the needlethrough the barrier.
 12. A syringe assembly, comprising: a cylinderhaving a fluid receiving cavity: a plunger having one end received inone end of the cavity; a floating barrier means received in the cavityand defining first and second chambers, said second chamber beinglocated intermediate the barrier meAns and the plunger; needle meansadjacent the other end of the cavity, said needle means projecting intoand communicating with said first chamber, said needle means puncturingthe barrier means and communicating with the second chamber when thebarrier means is moved toward the needle means responsive to movement ofthe plunger into the cavity; means for capturing the barrier meansadjacent the other end of the cavity with the needle means communicatingwith the second chamber, whereby the plunger may be withdrawn forsubsequent use of the second chamber in pumping fluid means forrelieving pressure in the first chamber at least prior to completepassage of the needle through the barrier means.
 13. The syringeassembly of claim 12 wherein the capturing means comprises, an enlargedportion of the needle means for retaining the barrier means after theneedle means punctures the barrier means.
 14. The syringe assembly ofclaim 13 wherein the enlarged portion of the needle means comprises acone adjacent the puncturing end of the needle means.
 15. The syringeassembly of claim 13 wherein the enlarged portion of the needle meanscomprises a barb adjacent the puncturing end of the needle means. 16.The syringe assembly of claim 12 wherein the capturing means comprises,an enlarged portion on the inner surface of the cylinder and locatedadjacent the barrier means in the second chamber after the barrier meansis punctured by the needle means.
 17. The syringe assembly of claim 16wherein the enlarged portion comprises a plurality of bosses on theinner surface of the cylinder.